The present invention relates to a control valve for influencing the tire pressure of a vehicle wheel having a valve chamber that on one end is connected to the interior of a tire of the wheel and on the other end is connected to a supply duct and a control duct. The valve chamber has a penetrating space that axially penetrates a wheel hub and is sealed off with respect to an axle part carrying the vehicle wheel. The control valve has an automatically closing valve means, and a control piston means acted upon by a pressure medium via the control duct for directing the automatically closing valve means into an open position against the interior pressure of the tire. The supply duct and the control duct extend through the axle part and air is suppliable to and removable from the supply duct via a supply control valve. The control duct is connectable with a fluid pressure medium source at least while air is simultaneously removed from the supply duct.
A control valve of this general type is known from German Published Unexamined Patent Application No. 25 44 555 (FIG. 2). It forms the conventional supply valve located on the outside at the vehicle wheel, in the chamber of which, coaxially to the automatically closing valve member, the control piston is guided that is used for the control of the supply valve. The supply duct is connected at the valve chamber coaxially to the control piston. The control piston is penetrated by an axial duct. In order to increase the tire pressure, compressed air is admitted to the control piston, whereby it directs the valve member into its open position. At the same time, compressed air, through the axial duct of the control piston, flows into the tire.
In order to reduce the pressure, compressed air is also admitted to the control piston for the opening of the control valve. However, in this circumstance, air is supplied to the control valve that has a pressure that is sufficient for producing the piston force required for opening the valve, but also permits a flowing-off of the air that is under a higher pressure from the vehicle tire.
Because of the air that is present in the supply duct at a relatively low pressure, the removal of air from the tire, in this case, takes place correspondingly slowly, the small cross-section of the valve opening also contributing to the slow removal of air.
In addition to the construction according to German Published Unexamined Patent Application No. 25 44 555, an arrangement is known from German Published Unexamined Patent Application No. 31 27 646 for supplying and removing tire air, which has a space that axially penetrates the wheel hub and a countershaft output gear wheel fastened on its rear side. The interior end of this space is sealed off with respect to an axle part carrying the vehicle wheel. A hollow-cylinder-shaped projection of the axle part projects into this space, this projection forming a connecting nipple to an air duct provided in the axle part. In that construction, no automatically closing valve is provided at the vehicle wheel or in the addressed space, but the tire pressure is maintained via an air source provided outside the vehicle wheel and a valve.
The present invention has the objective of providing a control valve for influencing the tire pressure of a vehicle wheel that permits a supplying and removing of tire air that can be carried out in a short period of time, and distinguishes itself by its secure arrangement with respect to output influences and easy connection.
This and other objects are achieved by the present invention by providing a control valve for influencing the tire pressure of a vehicle wheel which has a control piston means that is penetrated by an axial duct, and the axle part has a nonbearing cylindrical projection that is penetrated by the supply duct, this cylindrical projection projecting into the axial duct. The axle part and the control piston define an annular intermediate space therebetween, the control duct leading out into this annular intermediate space.
The valve member and the control piston of the control valve according to the present invention are located within a vehicle wheel in the area of the axle part that carries it. For supplying and removing tire air as well as for the adjusting of the control piston for the opening of the control valve, separate ducts are provided for which the arrangement of special lines is not necessary. The passage cross-section of the valve opening is therefore able to be several times larger than a conventional tire filling valve, and for the removal of air, the supply duct is connected directly with the atmosphere.
Other objects, advantages and novel features of the present invention will become apparent from the following detailed description of the invention when considered in conjunction with the accompanying drawings.